Thomas o



i ToaZZ whomz'tmay concern: y Be it known that I, THOMAS ,G.`BALL, of 1`Walpole; inthe county of Cheshire, in `the State of `Ne`wHaInp`shire,have invented a hereby declare'thatftlie following is aull ing hadtothe` accompanying drawings and to the letters of reference markedthereon.` `The natureof myinvention consistsin Q providing an iron standof similarorm-to those in cominonuselfor jack screw stands withtwoscrews, `instead of one, as is lcom- @inonly done, saidscrews being onewithin `the other and havingftheir threads cutin `opposite directions inorder that by turn-` y ingthe outer screw`,"both are elevated, in `thetimefusuallyv employed to elevate a` sin- I, gle screw, and,`fatfthesametime securing doublefheightjto that y acquired by theyordinaryjacksorewyfaswill more fully appear from theffollowing description and t`drawings accompanying.`

` screw ttedwithinjsaid stand.

l C, representsthe interior screw which is ittedwithin` the tubularscrewB.` Thetu- 3 l "bular screw B hasfformed upo-n its outer sur- "face, atright hand thread, having its counterpartwithinthe stand A, and workingthereinlilte any ordinary screw; while the interior screw C, has formedupon its outer `surfacea left hand thread, and has `its counter partwithin thetubular screw \B, working in like manner within said tubularscrew B.; f 1

`scMiur-JACK.V n

" `new and Improved4 Jack-Screw;fand I do,

*and exact description thereof, `reference be' A, represents thestand;B, the tubular M l described.

l UNITEDSTATESPATENT OFFICE.

` 1Q frHoMAs c. BALL, or. wALr-"omay NEW HAMPSHIRE.`

spcicationhof Letters Patent No. 12,464, dated February 27, 1855.

Fromlthis description it will clearly appear, that, while the load orbody to beA elevated lrests upon the interior screw C and prevents thesame from revolving about its centers, the tubular screw is left atliberty to berevolved by the operater, and while working, as aforesaidwithin the stand A, and elevating by means of its right hand threadg italso, at the same time, operates upon the interior screw C, by'ineans ofits interior screw C. Hence is secured, by the revolution of the tubularscrewB, double .the elevation tothe load, which is ordinarily attainedby the single screws in comfleft hand 7"thread, and thus elevates thescrews, nor any of the forms thereof, heretofore used; and I am awarethat a jack screw has been constructed in `which the center piece hastwo opposite threaded screws, one on each end and working in two femalescrews, one above and the other belowbut `What I claim, &c., is Thecombination 'of the tubular screw B with the standard A and the innerscrew C, the whole being arranged substantially as and for thepurposeabove set forth and n THos. c. BALL.

Witnesses i Y i SL M. BATES, n FREDERICK Vosr..

